An UWB Hemispherical Vivaldi Array

TL;DR

This paper introduces a conformal ultra-wideband hemispherical array with a novel mesh-based design, achieving wide-angle electronic scanning and near-theoretical gain performance from 2-18 GHz.

Contribution

It presents the first conformal UWB array on a doubly curved surface, using a quadrilateral mesh for systematic arraying and a titanium 3D-printed prototype with high scan angles.

Findings

Measured gain within 2 dB of theoretical from 2-18 GHz

Achieves scan angles up to 120° from the z-axis

Field of view is twice that of a comparable planar array

Abstract

We report the first conformal ultra-wide band (UWB) array on a doubly curved surface for wide angle electronic scanning. We use a quadrilateral mesh as the basis for systematically arraying UWB radiators on arbitrary surfaces. A prototype consisting of a 52 element, dual-polarized Vivaldi array arranged over a 181 mm diameter hemisphere is developed. The antennas and SMP connectors are 3D printed out of titanium to allow for simple fabrication and assembly. We derive the theoretical gain of a hemispherical array based on the antenna size and number of elements. The measured realized gain of the prototype array is within 2 dB of the theoretical value from 2-18 GHz and scan angles out to 120{\deg} from the z-axis. This field of view is twice that of a planar array with the same diameter in agreement with theory. This work provides a baseline performance for larger conformal arrays that have more uniform meshes. Furthermore, the basic concept can be extended to other UWB radiating elements.